Results 31 to 40 of about 68,053 (269)

High potential for weathering and climate effects of non-vascular vegetation in the Late Ordovician [PDF]

open access: yes, 2016
It has been hypothesized that predecessors of today’s bryophytes significantly increased global chemical weathering in the Late Ordovician, thus reducing atmospheric CO2 concentration and contributing to climate cooling and an interval of glaciations ...
A Boucot   +60 more
core   +3 more sources

Early Tremadocian cephalopods from Santa Rosita Formation in NW Argentina: the oldest record for South America [PDF]

open access: yesActa Palaeontologica Polonica, 2023
We describe early Tremadocian (Kainella meridionalis Biozone) cephalopods from the Cordillera Oriental, Jujuy, NW Argentina. They consist of numerous small specimens collected at the Quebrada de Arenal, Trancas section, near the town of Tilcara, in the
MARCELA CICHOWOLSKI   +5 more
doaj   +1 more source

High resolution carbon isotope stratigraphy of the basal Silurian stratotype (Dob's Linn, Scotland) and its global correlation [PDF]

open access: yes, 1997
Since its designation as the Global Stratotype Section and Point (GSSP) for the base of the Silurian System, the choice of Dob's Linn, Southern Scotland, has received criticism due to the difficulties of relating its well constrained graptolite ...
Brenchley, P.J.   +3 more
core   +1 more source

Note complementaire sur les echinodermes ordoviciens de Sierra Morena

open access: yesEstudios Geologicos, 1986
[fr] Une nouvelle espéce du genre Calix est décrite, le genre Batalleria est redécrit, la présence de Phlyctocystis dans les Monts de Toléde-Sierra Morena est confirmée, et celle de Destombesia est signalée.
J. Chauvel, B. Meléndez
doaj   +1 more source

Systematics, morphology, and appendages of an Early Ordovician pilekiine trilobite Anacheirurus from Fezouata Shale and the early diversification of Cheiruridae [PDF]

open access: yesActa Palaeontologica Polonica, 2021
Pilekiines are the earliest diverging members of the successful trilobite family Cheiruridae. The pilekiine genus Anacheirurus is characterized by sub-quadratic to sub-oval glabella, pitted genae, and a distinct trunk with elongated pleural spines in ...
FRANCESC PÉREZ-PERIS   +3 more
doaj   +1 more source

Rifting and arc-related early Paleozoic volcanism along the North Gondwana margin: geochemical and geological evidence from Sardinia (Italy) [PDF]

open access: yes, 2012
Three series of volcanic rocks accumulated during the Cambrian to Silurian in the metasediment-dominated Variscan basement of Sardinia. They provide a record of the changing geodynamic setting of the North Gondwana margin between Upper Cambrian and ...
BUZZI L   +3 more
core   +1 more source

EVENT STRATIGRAPHY AND CORRELATION PROBLEMS OF THE ORDOVICIAN STRATA OF GORNY ALTAI AND SALAIR

open access: yesГеодинамика и тектонофизика, 2021
Study of the Ordovician sedimentary sequences of Gorny Altai and Salair has revealed lithological and paleontological features correlating with global sedimentary events:(1) The Acerocare Regressive Event (an initial event in the Early Tremadocian);(2 ...
N. V. Sennikov   +5 more
doaj   +1 more source

The concealed Caledonide basement of eastern England and the southern North Sea : a review [PDF]

open access: yes, 1995
Field mapping, analysis of borehole core and studies of geophysical potential field and seismic data can be used to demonstrate the existence of a number of distinct crustal blocks within Eastern Avalonia beneath eastern England and the southern North ...
England, R., Lee, Mick, Pharaoh, Tim
core   +1 more source

Contrasting Early Ordovician assembly patterns highlight the complex initial stages of the Ordovician Radiation

open access: yesScientific Reports, 2022
The Early Ordovician is a key interval for our understanding of the evolution of life on Earth as it lays at the transition between the Cambrian Explosion and the Ordovician Radiation and because the fossil record of the late Cambrian is scarce.
Farid Saleh   +12 more
doaj   +1 more source

Metal enrichment in lithologically complex black shales: a case study from the Tremadocian of NE Estonia [PDF]

open access: yesEstonian Journal of Earth Sciences, 2021
Significantly elevated U, Mo, Zn and Pb contents characterize the Early Ordovician black shales in the Sillamäe area, NE Estonia. The presence of silty interlayers with sulphidic mineralization and authigenic carbonates suggests unique physicochemical ...
Rutt Hints   +4 more
doaj   +1 more source

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